Preseismic deformation in the seismogenic zone of the Lushan MS7.0 earthquake detected by GPS observations

作     者：LIU XiaoXia WU YanQiang JIANG ZaiSen ZHAN Wei LI Qiang WEI WenXin ZOU ZhenYu Liu X X;Wu Y Q;Jiang Z S;Zhan W;Li Q;Wei W X;Zou Z Y

作者机构：Institute of GeologyChina Earthquake Administration Key Laboratory of Earthquake PredictionChina Earthquake Administration First Crust Monitoring and Application CenterChina Earthquake Administration 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2015年第58卷第8期

页      面：1592-1601页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41274008,41104004) the Basic Research Project of Institute of Earthquake Science of China Earthquake Administration(Grant No.2014IES010101) 

主　　题：Lushan Ms7.0 earthquake GPS observations GPS baseline time series strain time series 

摘      要：A continuous GPS array across the southern segment of the Longmenshan fault zone recorded the deformation during the process of the Lushan MS7.0 earthquake that occurred on April 20, 2013. Such data can provide meaningful information regarding the dynamic evolution of crustal deformation in the seismogenic zone. Our studies have shown that the occurrence of the Wenchuan earthquake led to the loading of compressive and sinistral shearing strain on the southern segment of the Maoxian-Wenchuan fault, whereby the extrusion strain accumulated at a greater rate than before the Wenchuan earthquake. The strain time series in the seismogenic zone revealed that the principal compression strain rates decreased from west to east in the direction of N30°–45°W. Furthermore, the area to the east of Beichuan-Yingxiu fault behaved as a zone of compressive deformation with obvious sinistral shearing deformation. The surface strain and the first shearing strain time series decreased with time, while the area to the west of the Beichuan-Yingxiu fault behaved as a zone of dextral shear deformation that increased with time. Furthermore, the regional deformation field before the Lushan earthquake showed that the rate of extrusion strain accumulation in the southern segment of the Longmenshan fault zone was obviously larger than before the Wenchuan earthquake. Moreover, the sinistral shearing strain accumulated in the area of the southern segment of the Maoxian-Wenchuan fault. Based on the above analysis, we consider that the eastward movement of the Bayan Har block increased considerably following the Wenchuan earthquake, which enhanced the accumulation of compression strain in the southern segment of the Longmenshan fault zone.